When You Need a Blood Transfusion (Adult)

A blood transfusion may be done when you have lost blood because of an injury or during surgery. It can also be done because of diseases or conditions that affect the blood. Blood is made up of several different parts (blood products). You may receive some or all of these blood products during a transfusion. Blood for transfusion is usually donated from another person (donor). Strict measures are taken to make sure that donated blood is safe before it's given to you. This sheet helps you understand how a blood transfusion is done. Your healthcare provider will discuss your condition with you and answer your questions.  

The parts of blood

Blood can be broken down into different parts that perform special roles in the body. These parts include:

  • Red blood cells, which carry oxygen throughout the body.

  • Platelets, which help stop bleeding.

  • Plasma (the liquid part of blood), which carries red blood cells and platelets throughout the body. Plasma also helps platelets in stopping bleeding.

Where does donated blood come from?

  • Volunteer donors. These are people who donate their blood to help others in need of blood. Blood donation can take place at several places, including a hospital, blood bank, or during a blood drive.

  • Directed donation. If you need a blood transfusion during a planned surgery, family and friends can have their blood tested for compatibility and donate blood for you before the surgery. This needs to be done at least 7 day(s) in advance. This is because the blood must be tested for safety.

  • Autologous donation. This is also called self-donation. For planned surgery, you can donate your own blood starting up to 6 weeks before surgery.

Are blood transfusions safe?

Donated blood is tested and processed to make sure that the blood is safe:

  • The health and medical history of each donor is carefully screened. If a person is considered high-risk for infection or problems, he or she isn't accepted as a blood donor.

  • Donated blood is tested for infections such as hepatitis, syphilis, and HIV (the virus that causes AIDS). If the tested blood is found to be unsafe, it's destroyed.

  • Blood is divided into four types: A, B, AB, and O. Blood also has Rh types: positive (+) and negative (-). You can only receive blood products that are compatible with (match) your blood type. A sample of your blood is tested for compatibility with donated blood. This is done before blood products are prepared for a transfusion.

How is a blood transfusion done?

A blood transfusion takes place in a blood center, infusion center, hospital room, or operating room. Your healthcare provider will discuss the blood transfusion with you before it's done. You'll need to give permission for the blood transfusion by signing a consent form.

  • Two healthcare providers confirm your identity. They also confirm that they have the correct blood product(s) for you.

  • An intravenous (IV) line is placed in a vein if you do not already have an IV.

  • The blood product comes in a plastic bag that is hung on an IV pole. The blood product flows from the bag into your IV line. The IV line may be connected to a pump, which controls the transfusion rate. You may receive more than one kind of blood product through the IV.

  • Your vital signs (blood pressure, heart rate, respiratory rate, and temperature) are checked throughout the transfusion. This is to make sure you are not having a reaction to the blood product.

  • The IV line may be removed once the transfusion is complete.

Possible risks and complications of blood transfusions

Most transfusions are problem free. In some cases, reactions occur. These can happen within seconds to minutes during the transfusion or a week to a few months after the transfusion. Call your doctor or nurse right away if you have any of the signs or symptoms in the table below during or after a transfusion:




Allergic reaction (mild)

  • Within seconds to minutes during the transfusion

  • Up to 24 hours after the transfusion

Hives or red welts on the skin, mild itching, rash, localized swelling, flushing (red face), wheezing, shortness of breath, or stridor (high-pitched noise or sound)

Anaphylactic reaction

  • Within seconds to minutes during the transfusion

  • Up to 24 hours after the transfusion

Shortness of breath, flushing (red face), wheezing, labored (working hard) breathing, low blood pressure, localized swelling, chest tightness, or cramps

Febrile nonhemolytic reaction

  • Within minutes to hours during the transfusion

  • Within a few hours to 24 hours after the transfusion

Fever (increase of 1° C or higher), chills, flushing (red face), nausea, headache, minor discomfort, or mild shortness of breath

Acute immune hemolytic reaction

  • Within minutes during the transfusion

  • Up to 24 hours after the transfusion

Fever, red or brown urine, back pain, fast heart rate (tachycardia), abdominal pain, low blood pressure, feeling anxious, chills, chest pain, nausea, or fainting spells

Transfusion-related acute lung injury (TRALI)

  • Within 1 to 2 hours during the transfusion

  • Up to 6 hours after the transfusion

Shortness of breath, trouble breathing, low blood pressure, fever, pulmonary edema

Transfusion-associated circulatory overload

  • Near the end of the transfusion

  • Within 6 hours after the transfusion

Shortness of breath, fast heart rate (tachycardia), problems breathing when lying on back, abnormal blood pressure

Post-transfusion purpura (PUP)

  • Within 1 week

  • Up to 48 days after the transfusion

Purple spots on skin; nose bleed; bleeding from the urinary tract, abdomen, colon, or rectum; fever; or chills



"Delayed" transfusion-related acute lung injury (TRALI)

  • Within 72 hours (3 days) after the transfusion

"Sudden" onset of respiratory distress or trouble breathing

"Delayed" hemolytic reaction

  • Within 3 to 7 days

  • Up to weeks after the transfusion

Low-grade fever, mild jaundice (yellowing of the skin and whites of the eyes), decrease in hematocrit, chills, chest pain, back pain, nausea